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{\LARGE\bf Chinese Journal of Astronomy and Astrophysics}\\

2006, Vol.6, No.3 (June 20, 2006)



Extragalactic Astronomy

Stellar Clusters


The Sun

Astrometry and Celestial Mechanics

Instruments, Observational Techniques and Data Processing


Stellar Abundance and Galactic Chemical Evolution through LAMOST Spectroscopic Survey

Gang Zhao1, Yu-Qin Chen1, Jian-RongShi1, Yan-Chun Liang1, Jin-Liang Hou2, Li Chen2, Hua-Wei Zhang3 and Ai-Gen Li1, 4

1 National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012; gzhao@bao.ac.cn
2 Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030
3 Department of Astronomy, School of Physics, Peking University, Beijing 100871
4 Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211, USA

A project of a spectroscopic survey of Galactic structure and evolution with a Large sky Area Multi-Object fiber Spectroscopic Telescope (LAMOST) is presented. The spectroscopic survey consists of two observational modes for various targets in our Galaxy. One is a major survey of the Milky Way aimed at a systematic study of the stellar abundance and Galactic chemical evolution through low resolution (R = 1000-2000) spectroscopy. Another is a follow-up observation with medium resolution (R = 10000) spectrographs aimed at detailed studies of the selected stars with different chemical composition, kinematics and dynamics.

Key Words:   techniques: spectroscopic -- stars: abundances -- Galaxy: structure -- Galaxy: abundances -- Galaxy: kinematics and dynamics -- Galaxy: evolution
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SDSS J143030.22-001115.1: A Misclassified Narrow-line Seyfert 1 Galaxy with Flat X-ray Spectrum

Wei-Hao Bian1, 2, Quan-Ling Cui1 and Li-Hua Chao1

1 Department of Physics and Institute of Theoretical Physics, Nanjing Normal University, Nanjing 210097 whbian@njnu.edu.cn
2 Key Laboratory for Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049

We used multi-component profiles to model the H$\beta$ and [OIII] $\lambda \lambda $4959,5007 lines of SDSS J143030.22-001115.1, a narrow-line Seyfert 1 galaxy (NLS1) in a sample of 150 NLS1 candidates selected from the Sloan Digital Sky Survey (SDSS), Early Data Release (EDR). After subtracting the H$\beta$ contribution from narrow line regions (NLRs), we found that its full width half maximum (FWHM) of broad H$\beta$ line is nearly 2900, significantly larger than the customarily adopted criterion of 2000. With its weak FeII multiples, we believe that SDSS J143030.22-001115.1 should not be classified as a genuine NLS1. When we calculate the virial black hole masses of NLS1s, we should use the H$\beta$ linewidth after subtracting the NLR component.

Key Words:   galaxies: active -- galaxies: emission lines -- galaxies: nuclei -- galaxies: Seyfert -- galaxies:individual: J143030.22-001115.1
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Kinematics of the Open Cluster System in the Galaxy

Jun-Liang Zhao, Li Chen and Zhong-Liang Zu

Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030 chenli@shao.edu.cn

Absolute proper motions and radial velocities of 202 open clusters in the solar neighborhood, which can be used as tracers of the Galactic disk, are used to investigate the kinematics of the Galaxy in the solar vicinity, including the mean heliocentric velocity components (u1, u2, u3) of the open cluster system, the characteristic velocity dispersions $(\sigma
_1, \sigma _2, \sigma _3)$, Oort constants (A, B) and the large-scale radial motion parameters (C, D) of the Galaxy. The results derived from the observational data of proper motions and radial velocities of a subgroup of 117 thin disk young open clusters by means of a maximum likelihood algorithm are: $(u_1, u_2, u_3)=(- 16.1\pm 1.0, - 7.9\pm 1.4, - 10.4\pm 1.5)  \mbox{km
s}^{ - 1}$, $(\sigma _1, \sigma _2, \sigma _3 ) = (17.0\pm 0.7, 12.2\pm 0.9,
8.0\pm 1.3\mbo...
(A, B) = (14.8\pm 1.0, - 13.0\pm
2.7\mbox{) ~km s}^{ - 1}\mbox{ ~kpc}^{ -1},$ and $(C,D) = (1.5\pm
0.7, - 1.2\pm 1.5\mbox{) km s}^{ - 1}\mbox{ kpc}^{ -1}$. A discussion on the results and comparisons with what was obtained by other authors is given.

Key Words:   Galaxy: kinematics and dynamics -- open clusters and associations: general
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The Origin of Glitches in Pulsars -- Phase Oscillation between Anisotropic Superfluid and Normal State of Neutrons in Neutron Stars

Qiu-He Peng1, 2, Zhi-Quan Luo1, 3 and Chih-Kang Chou4

1 School of Physics and Electronic Information, China West Normal University, Nanchong 637002
2 Department of Astronomy, Nanjing University, Nanjing 210093; qhpeng@nju.edu.cn
3 Department of Physics, Sichuan University, Chengdu 610065
4 National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012

Considering neutron star heating by magnetic dipole radiation from 3PF2 superfluid neutron vortices inside the star, we propose a neutron phase oscillation model between the normal neutron Fermi fluid and the 3PF2 superfluid neutron vortices at the transition temperature of $T_{\rm trans} =
(2-3)\times 10^8$K. With this model we can qualitatively explain most of the observations on pulsar glitches up to date.

Key Words:   stars: neutron -- pulsars: general
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On the Evolution of the Apparent Size of Gamma-Ray Burst Remnants

Ting-Ting Gao and Yong-Feng Huang

Department of Astronomy, Nanjing University, Nanjing 210093; hyf@nju.edu.cn

The remnants of two gamma-ray bursts, GRB 030329 and GRB 041227, have been resolved by Very Long Baseline Interferometry observations. The radio counterparts were observed to expand with time. These observations provide an important way to test the dynamics of the standard fireball model. We show that the observed size evolution of these two events cannot be explained by a simple jet model, rather, it can be satisfactorily explained by the two-component jet model. It strongly hints that gamma-ray burst ejecta may have complicated structures.

Key Words:   gamma rays: bursts -- ISM: jets and outflows
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Relative Spectral Lag: a New Redshift Indicator of Gamma-ray Bursts

Zhi-Bin Zhang 1, 4, Jia-Gan Deng 1, 2, Rui-Jing Lu 1, 2, 4 and Hai-Feng Gao 3

1 National Astronomical Observatories/Yunnan Observatory, Chinese Academy of Sciences, Kunming 650011; zbzhang@ynao.ac.cn
2 Physics Department, Guangxi University, Nanning 530004
3 Sishui, No. 2 Middle School, Shandong 273206
4 Graduate School of Chinese Academy of Sciences, Beijing 100049

Using 64 ms count data of long gamma-ray bursts (T90> 2.6s), we analyze the quantity named relative spectral lag (RSL), $\tau_{31}/{\rm FWHM}_{(1)}$. We investigated in detail all the correlations between the RSL and other parameters for a sample of nine long bursts, using the general cross-correlation technique that includes the lag between two different energy bands. We conclude that the distribution of RSLs is normal and has a mean value of 0.1; that the RSLs are weakly correlated with the FWHM, the asymmetry, peak flux (Fp), peak energy (Ep) and spectral indexes ($\alpha$ and $\beta$), while they are uncorrelated with $\tau_{31}$, the hardness-ratio (HR31) and the peak time (tm). Our important discovery is that redshift (z) and peak luminosity (Lp) are strongly correlated with the RSL, which can be measured easily and directly, making the RSL a good redshift and peak luminosity indicator.

Key words:   gamma-rays: bursts -- methods: data analysis
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A One-Dimensional Relativistic Shock Model for the Light Curve of Gamma-ray Bursts

Cheng-Yue Su1, 2, 3, Yi-Ping Qin 1, Jun-Hui Fan4, and Zhang-Yu Han5

1 National Astronomical Observatories/Yunnan Observatory, Chinese Academy of Sciences, Kunming 650011; su_cy@163.com
2 Graduate School of Chinese Academy of Sciences, Beijing 100049
3 Department of Physics, Guangdong University of Technology, Guangzhou 530004
4 Center for Astrophysics, Guangzhou University, Guangzhou 510400
5 Department of Mechanics, University of Science and Technology of China, Hefei 230026

We investigate the forming of gamma-ray burst pulses with a simple one-dimensional relativistic shock model. The mechanism is that a ``central engine" drives forward the nearby plasma inside the fireball to generate a series of pressure waves. We give a relativistic geometric recurrence formula that connects the time when the pressure waves are produced and the time when the corresponding shocks occurred. This relation enables us to relate the pulse magnitude with the observation time. Our analysis shows that the evolution of the pressure waves leads to a fast rise and an exponential decay pulses. In determining the width of the pulses, the acceleration time is more important than that of the deceleration.

Key Words:   gamma-ray: bursts -- profiles -- hydrodynamics -- shock waves -- methods: numerical
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On the Period Variation of the W UMa-type Contact Binary V502 Ophiuchi

Qing-Yao Liu and Yu-Lan Yang

National Astronomical Observatories/Yunnan Observatory, Chinese Academy of Sciences, Kunming 650011; bily@public.km.yn.cn

The variation in the orbital period of the W UMa type contact binary V502 Oph is analyzed. The orbital period exhibits a wavelike variation with a periodicity of 23.0 years and an amplitude of $\Delta{P}=1.24\times10^{-6}$ days superimposed on secular decrease of dP/dt=1.68 x 10-7 day per year. The long-term decrease may be accompanied by the contraction of the secondary at a rate of 83 m per year and a mass transfer rate from the primary to the secondary of $4.28\times10^{-8}M_{\sun}$ per year. The short-term oscillation may be explained by the presence of a third component. Orbital elements of the third body and its possible mass are presented.

Key Words:   stars: contact binary -- period change -- star: individual: V502 Oph)
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A New Method to Determine Epochs of Solar Cycle Extrema

Zhan-Le Du1, 2, Hua-Ning Wang2 and Xiang-Tao He1

1 Department of Astronomy, Beijing Normal University, Beijing 100875; zldu@bao.ac.cn
2 National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012

A weighted average method is proposed to determine the epochs of solar cycle extrema and hence the solar cycle lengths. Comparing to the previous methods, this method has the advantage that the extremum epochs are easily and uniquely determined.

Key Words:   Sun: activity -- Sun: sunspots -- Sun: general
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The Filament Eruption of 1999 March 21 and Its Associated Coronal Dimmings and CME

Yun-Chun Jiang, Le-Ping Li and Li-Heng Yang

National Astronomical Observatories/Yunnan Observatory, Chinese Academy of Sciences, Kunming 650011; jyc@ynao.ac.cn

We report a filament eruption near the center of the solar disk on 1999 March 21, in multi-wavelength observations by the Yohkoh Soft X-Ray Telescope (SXT), the Extreme-ultraviolet Images Telescope (EIT) and the Michelson Doppler Imager (MDI) on the Solar and Heliospheric Observatory (SOHO). The eruption involved in the disappearance of an H${\alpha}$ filament can be clearly identified in EIT 195Å difference images. Two flare-like EUV ribbons and two obvious coronal dimming regions were formed. The two dimming regions had a similar appearance in lines formed in temperature range 6 x 104K to several 106K. They were located in regions of opposite magnetic polarities near the two ends of the eruptive filament. No significant X-ray or H${\alpha}$ flare was recorded associated with the eruption and no obvious photospheric magnetic activity was detected around the eruptive region, and particularly below the coronal dimming regions. The above surface activities were closely associated with a partial halo-type coronal mass ejection (CME) observed by the Large Angle and Spectrometric Coronagraphs (LASCO) on the SOHO. In terms of the magnetic flux rope model of CMEs, we explained these multiple observations as an integral process of large-scale rearrangement of coronal magnetic field initiated by the filament eruption, in which the dimming regions marked the evacuated feet of the flux rope.

Key Words:   Sun: activity -- Sun: filaments -- Sun: coronal mass ejections(CMEs) -- Sun: magnetic fields
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Evolution of the Level of Sunspot Activity in Solar Cycles I. Evolution in the Descending Phase

Jia-Long Wang

National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012; wjl_nao@hotmail.com

Taking the 13-point smoothed monthly sunspot number, Ri, and the deviation of the 13 associated monthly sunspot numbers from the smoothed one, Di, as a number-pair describing the global level of sunspot activity, the evolution of the level is statistically studied for the period from the month which is just 48 months before the minimum to the minimum in the descending phase, using the observed data of Solar Cycles 10 to 22. Our results show (1) for 46 months (94%) of the studied 49 months it is found that for a given month, the distribution of the 13 pairs which come from the 13 solar cycles on a $\log R_i\sim D_i$ plane may be fitted by a straight line with a correlation coefficient larger than the critical one at confidence level $\alpha = 5$%, and for 36 months (73%) the fitting is even better, for $\alpha = 1{\%}$; (2) time variations of these two parameters and their correlations in the studied period can be described respectively by functions of time, whose main trends may be expressed by a linear or simple curvilinear function; (3) the evolutionary path of the level of sunspot activity may be represented by a logarithmic function as $\log R_i = 0.704 \ln D_i
- 0.291$.

Key Words:   Sun -- sunspots -- active level evolution
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Velocity Space of Galactic O-B Stars

Zi Zhu

Department of Astronomy, Nanjing University, Nanjing 210093; zhuzi@nju.edu.cn

Based on the Hipparcos proper motions and available radial velocity data of O-B stars, we have re-examined the local kinematical structure of the young disk population of $\sim1500$ O-B stars not including the Gould-belt stars. A systematic warping motion of the stars about the direction to the Galactic center has been reconfirmed. A negative K-term implying a systematic contraction of stars in the solar vicinity has been detected. Two different distance scales are used in order to find out their impact on the kinematical parameters, and we conclude that the adopted distance scale plays an important role in characterizing the kinematical parameters at the present level of the measurement uncertainty.

Key Words:   astrometry -- Galaxy: kinematics and dynamics -- stars: early-type -- Galaxy: solar neighborhood
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On the Station-Keeping and Control of the World Space Observatory/Ultraviolet

Xi-Yun Hou 1,2, Hai-Hong Wang 1,2 and Lin Liu 1,2

1 Department of Astronomy, Nanjing University, Nanjing 210093; xhliao@nju.edu.cn
2 Institute of Space Environment and Astronautics, Nanjing University, Nanjing 210093

Collinear libration points play an important role in deep space exploration because of their special positions and dynamical characteristics. Since motion around them is unstable, we need to control the spacecraft if we wish to keep them around such a libration point for a long time. Here we propose a continuous low-thrust control strategy, illustrated with numerical simulations combined with the orbit design and control of the World Space Observatory/UltraViolet (WSO/UV).

Key Words:   celestial mechanics -- WSO/UV -- low thrust
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VOFilter: Bridging Virtual Observatory and Industrial Office Applications

Chen-Zhou Cui1, Markus Dolensky2, Peter Quinn2, Yong-Heng Zhao1 and Françoise Genova3

1 National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012; ccz@bao.ac.cn
2 European Southern Observatory, D-85748 Garching bei München, Germany
3 CDS, Observatoire Astronomique de Strasbourg, France

VOFilter is an XML based filter developed by the Chinese Virtual Observatory project to transform tabular data files from VOTable format into OpenDocument format. VOTable is an XML format defined for the exchange of tabular data in the context of the Virtual Observatory (VO). It is the first Proposed Recommendation defined by International Virtual Observatory Alliance, and has obtained wide support from both the VO community and many Astronomy projects. OpenOffice.org is a mature, open source, and front office application suite with the advantage of native support of industrial standard OpenDocument XML file format. Using the VOFilter, VOTable files can be loaded in OpenOffice.org Calc, a spreadsheet application, and then displayed and analyzed as other spreadsheet files. Here, the VOFilter acts as a connector, bridging the coming VO with current industrial office applications. We introduce Virtual Observatory and technical background of the VOFilter. Its workflow, installation and usage are presented. Existing problems and limitations are also discussed together with the future development plans.

Key Words:   astronomical data bases: miscellaneous -- Virtual Observatory -- methods: data transform
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ChJAA, 2006, Vol.6, No.3

Chinese Journal of Astronomy and Astrophysics: Online Edition


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